#4 Plank Jacks
Of all the exercises this is probably the most intense as it brings in a huge element of cardio. This exercise is a combination of a good old plank and jumping jacks. Thus you are in a plank position with either your elbows on the floor or your palms. Your entire body is parallel to the ground. Make sure your core is tight and absolutely straight. Then jump and open your legs and jump and get them back to the original position.
Initially, you can count the number of plank jacks and start by doing 20. But then as the fitness levels increase, you can time yourself. Thus doing plank jacks for a minute, maybe even 2!
Thus these are four effective ab exercises which you can do anywhere and you require absolutely no equipment for. These exercises have been chosen in a way that while they are extremely intense on the core they work other parts of the body too; arms, hamstrings, glutes and even your stamina. Happy working out!